One question comes up again and again: is 18k gold good? The short answer is yes. The useful answer is more nuanced. Karat measures one thing only, the proportion of pure gold in the alloy. It does not measure strength, quality of workmanship, or how long a piece will last. On one specific point, 18 karat gold is in fact worse than 14 karat. Here is what each fineness really changes, without the sales talk.

What karat actually means: 750, 585, 375

The karat of gold has nothing to do with the carat of a diamond. Two different units, one shared name. That is the first source of confusion.

For a diamond, a carat is a weight. One carat is 0.2 grams.

For gold, a karat is a proportion. The scale runs from 0 to 24. Pure gold is 24 karat. Each karat is therefore one twenty fourth of the alloy.

That is where the three numbers stamped on jewellery come from.

750. This is 18 karat gold. 750 parts per thousand of pure gold, or 75 %. The rest is an alloy of copper, silver or palladium depending on the colour wanted.

585. This is 14 karat gold. 585 parts per thousand, so roughly 58.5 % pure gold.

375. This is 9 karat gold. 375 parts per thousand, or 37.5 % pure gold. Less than half the metal is gold.

Remember one thing. Fineness tells you how much gold you are buying. It tells you nothing about the quality of the making, the precision of the setting, or how long the piece will survive. Those are separate questions, and the trade is happy to blur them. We take the hallmark apart in our article on what 750 really means.

Why French jewellery is almost always 18 karat

Here is the piece of context most English language guides leave out, and it explains why you barely ever see 14 karat in a Paris window.

French law recognises three finenesses for gold: 750, 585 and 375 parts per thousand. All three are legally gold. No ambiguity there.

But the French fine jewellery tradition settled on 18 karat, and the state guarantee system reflects that. A gold piece at 750 parts per thousand made in France carries the eagle's head hallmark. That is the French state mark certifying the fineness.

This framework is French. It does not apply elsewhere. In the United States, the working standard for fine jewellery is 14 karat. In the United Kingdom, 9 karat is very common. In India and the Middle East, 22 karat dominates. None of these markets is wrong. They are different habits, born of different climates, tax systems and relationships with gold.

So be wary of a common argument: « 18 karat is better because it is the standard ». A country's standard is not technical proof. What follows, on the other hand, is.

Hardness: the one point where 18k gold loses

Let us be straight about this, because almost nobody in the trade says it plainly.

Pure gold is a very soft metal. It scratches and deforms with surprising ease. It is the alloying metals, copper in particular, that bring hardness.

The consequence is mechanical. The higher the fineness, the smaller the share of alloy, and the softer the metal.

So 14 karat gold is harder than 18 karat gold. And 9 karat is harder still. That is a fact, not an opinion, and it means a 14 karat wedding band will keep its polish longer than an 18 karat band worn in the same conditions.

Does that make 14 karat the better metal? No, and here is why.

18 karat gold does not scratch dramatically. It takes on a patina, a fine network of micro scratches that softens the surface. Plenty of people end up preferring that patina to the original polish, and a workshop polish removes it in minutes.

More importantly, hardness does not decide longevity on its own. 18 karat gold is three quarters gold. It resists corrosion better, it does not tarnish, and it repairs better because its gold content allows clean solder work. 9 karat gold, with 62.5 % non noble metals, can tarnish and behave less predictably over time.

So the honest way to put it is this. 14 karat wins on scratch resistance. 18 karat wins on chemical stability, repairability and material value. On everyday care, see our article on the five enemies of gold jewellery.

Yellow gold or white gold: what the alloy does

At a given fineness, colour does not come from the gold. It comes from the remaining 25 %.

Yellow 18 karat gold combines gold with copper and silver in balanced proportions. The lower the fineness, the more the colour depends on the alloy, and the more it varies from one maker to the next. That is why yellow 9 karat gold can look pale or greyish depending on the workshop, while yellow 18 karat stays clean and warm.

White 18 karat gold combines gold with whitening metals such as palladium. The result is never perfectly white as it comes out. It keeps a slightly warm undertone. That is why white gold is rhodium plated, meaning coated with a very thin layer of rhodium, a platinum family metal that is cold white and chemically inert.

That layer wears. On a ring worn daily, it eventually marks at friction points and the warmer undertone of the alloy shows through. This is normal, it is not a defect, and re-rhodium plating is a workshop job.

One thing worth knowing if you are choosing a coloured stone. A yellow setting warms the perceived hue of a stone. A white setting lets it read as it is. A blue or green lab-grown diamond therefore looks cleaner on white 18 carat recycled gold, and softer on yellow.

High karat and sensitive skin

This is the strongest argument in favour of a high fineness, and oddly the least promoted.

Pure gold is chemically very unreactive. It practically never causes contact allergy. What reacts is the alloying metals.

Do the arithmetic. 18 karat gold contains 25 % alloy. 14 karat contains 41.5 %. 9 karat contains 62.5 %. Every step down in fineness multiplies the surface of contact with non noble metals.

The most common allergen in jewellery is nickel, long used to whiten and harden certain alloys. Nickel release from jewellery is now strictly regulated in Europe, but it remains very present in costume jewellery and in low grade steels.

If your skin reacts easily, the reasoning is simple. Go up in fineness. Recycled 18 carat gold is the most comfortable choice on this list.

What fineness really changes on the bill

A very common error in reasoning: assuming a 9 karat piece costs three times less than an 18 karat piece because it contains three times less gold.

It does not, and here is why.

The price of a piece breaks into three blocks. Material, meaning the metal and the stone. Labour, meaning casting, setting, polishing and quality control. And structure, meaning everything that keeps the workshop and the brand alive.

Only the first block moves with fineness. Setting a diamond takes exactly the same work in 9 karat as in 18 karat. The same hours. The same checks.

On a delicate piece, material is a modest share of the final price. Going down in fineness therefore saves far less than people imagine, while giving up chemical stability, skin tolerance and resale value.

On a heavy piece, a wide bangle for instance, the reasoning partly reverses. There, the mass of gold really does weigh on the bill, and the choice of fineness becomes a genuine budget lever.

That is also why we offer the same design in rhodium plated 925 silver, in vermeil and in recycled 18 carat gold rather than lowering the gold fineness. Dropping the karat means paying almost the same labour for a less stable metal. Changing metal is a clear trade-off. We costed it out in our comparison of silver, vermeil and recycled 18 carat gold.

Which karat for which piece

Down to specifics. The right fineness depends on the object, not on a general rule.

A ring worn every day, with no significant stone. 14 karat is defensible. It scratches less. If you live somewhere it is common and well made, it is a rational choice.

A ring with a stone held in claws. 18 karat is preferable. Claws need to be retipped and tightened over the years, and a gold rich metal reworks and re-solders far better.

Earrings. High fineness is the most comfortable, because the post sits for hours in contact with thin and often reactive skin.

A necklace or a pendant. Wear is minimal. Choose on colour and budget first.

A bracelet. It takes a lot of knocks against tables and door handles. Favour solid construction rather than fixating on fineness.

A piece meant to be handed down. 18 karat, without hesitation. Higher material value, better stability, better repairability.

What to remember

Fineness measures a proportion of gold, nothing else. It does not measure the quality of a piece or how long it will last.

18 karat gold is not the hardest. 14 karat scratches less, and that needs saying. In exchange, 18 karat is chemically more stable, better tolerated by reactive skin, easier to repair, and it holds real material value.

9 karat gold is genuine gold in law, but it contains more alloy metal than gold. On a delicate piece it saves little and weakens the rest.

Our own choice is made, and we own it: recycled 18 carat gold for the gold pieces, rhodium plated 925 silver and vermeil for the accessible line. No intermediate fineness, because the saving would not cover what you give up.

If you want to go deeper into this metal, our gold buying guide covers the basics, and our article on the advantages of 18 carat gold develops the case for the 750 alloy.

FAQ

Is 18k gold good for everyday jewellery?

Yes, with one caveat. It is chemically stable, does not tarnish, is well tolerated by sensitive skin and repairs cleanly. But it is softer than 14 karat, so it picks up micro scratches faster. On a claw set ring, 18 karat is still the better choice.

What is the difference between 18 karat and 14 karat gold?

The proportion of pure gold. 18 karat contains 750 parts per thousand, 14 karat contains 585. 14 karat is harder, so it scratches less. 18 karat is more stable, better tolerated by skin and holds higher material value.

Does 18 karat gold scratch easily?

More easily than 14 karat, yes. But it does not scratch dramatically: it takes a patina of micro scratches that a workshop polish removes in minutes. Many people end up preferring that patina to the factory finish.

What does 750 mean on gold jewellery?

That the metal contains 750 parts per thousand of pure gold, that is 75 %, that is 18 karat. It is the most common fineness in French fine jewellery. In France, a gold piece at 750 carries the eagle's head guarantee hallmark, a French state mark.

Is 9 karat gold real gold?

Yes in law. It is 375 parts per thousand, recognised in France as across Europe. But 62.5 % of the metal is not gold, which makes it less stable over time and less well tolerated by reactive skin.

What is the purity of 18 carat gold?

75 % pure gold, expressed as 750 parts per thousand. The remaining 25 % is an alloy of copper, silver or palladium, chosen according to the colour of the finished metal.

Is 18k gold good for sensitive skin?

It is the best of the three finenesses. Three quarters of the metal is pure gold, which is very unreactive. The lower the fineness, the larger the share of alloy, and the higher the risk of a contact reaction.

Why does French jewellery mostly use 18 carat gold?

Tradition, and consistency with the state guarantee system. All three finenesses are legal in France, but the fine jewellery trade settled on 750 parts per thousand, and the eagle's head hallmark is the marker of it. That is a French convention, not a universal rule.

Fiona